Detroit / General Motors / GM Diesel

Series 53, 72 and 92 Engine Specifications

The older Denning Mono and Austral Tourmaster coaches are powered by a variety
of General Motors (GM) diesels, generally referred to as “Detroit” diesels.
The series identifier gives an idea as to the age and size of the motor — most
early-to-mid 1980’s coaches seem to be fitted with a series 71; series
92 a bit later; series 53 earlier. So to compare the specifications of Australs
and Dennings we wanted to know something about the various Series 53, 71 and
92 diesels. The tables below are incomplete, and include industrial versions,
but provide a good starting point.

Most Motorhome/Recreational Vehicle (RV) owners didn’t know the finer
details of their engines. Typically they knew it was a “Detroit” and
the number of cylinders. Info from bus/coach lines depended on the technical
background of the person handling the sale.

Happily, a great deal of information about a Detroit motor can be deduced
just from the engine number. An engine number that starts with or includes
6VF or 6VA is likely to be Series 92, and so on for the different series. On
the Detroit engines the model number can be stamped immediately below the serial
number. Sometimes the engine number recorded on the registration paperwork
includes the complete or partial model number that could identify the engine
type. For example, the last eight digits of 6VF08130480677840 gives the model
number 8067-7840, which in Australia would be a 6V92TTA. (Because of different
pollution standards many US sites will identify an 8067-7840 motor as a 6V92TA,
except in California, where it would be a 6V92TTA).

The basic series naming convention is pretty logical: the initial digit is
the number of cylinders, usually followed by a “V” for the cylinder
configuration; the next two give the displacement in cubic-inches per cylinder
(the 53, 71 and 92 series all follow this convention; later series , such as
the 60 series, don’t). A“T” suffix indicates turbocharged;
an“A” means aftercooled. Thus a “671” is a natually-aspirated
7 litre inline 6, while a “6V92TA” is a 9 litre turbocharged aftercooled
V6. Some background on the Detroit diesels is available on Wikipedia (see Series
71, Series 92, and
related pages). There’s a nice article here comparing
the Detroits with similar-sized 4-stroke diesels for the moderately technically-inclined.

The tables below lists the SAE Rated Gross Power in kW and BHP (brake horsepower)
for the various models, with links to the specification sheet for each. The
rating is typically (but not always) at 2100 rpm. The same engine
model can have different power ratings due to different injectors or other
variations. There are some engines here that would never be fitted to a bus.